The flycutter is a familiar apparatus for finish machining, providing extremely fine surface conditioning of metal and other hard substrates. The flycutter apparatus has a rotatable flywheel, also termed a flycutter plate or flycutter wheel, with an attached tool that repeatedly scores the surface of a workpiece, slowly advancing the workpiece into the tool path along a slide mechanism to achieve a highly precise finish. Typically fitted with a diamond tool, the cutting, scoring, or scribing action of the flycutter obtains a highly polished surface with roughness precision that can be at sub micron levels. With crystals and non ferrous metals, the flycutter action not only removes material as it is scored, but can be inherently self-cleaning, wherein the particulate is continually swept away from the tool point and surface by the cutting action as finishing proceeds.
With recent advances in diamond tool fabrication and use, the flycutter apparatus has been adapted for use in finishing of precision optical devices that require ultra-flat and smooth surfaces. For optical finishing, however, unlike its use with metals and crystalline materials, the flycutter tool and workpiece surface can be exceedingly difficult to keep clean. The high speed spinning action of the flycutter, with typical ranges of 1500 RPM and higher, tends to cause a vacuum. Filings and other particulate and residue from the machining process, generally termed “swarf”, can be sucked inwards, toward the axis of rotation. This problem can be particularly troublesome with optical materials such as poly(methyl methacrylate) (PMMA), polystyrene, cyclic olefin, polyetherimide and other amorphous polymers. Since the diamond cutting tool and polymer workpiece are electric insulators, the friction between the tool and workpiece, during scission, generates static and heat. This results in a fine, static charged swarf which is difficult to remove from the workpiece and tooling.
Some of the conventional swarf removal methods, such as cutting fluids, are not applicable to polymers. Some polymers are hygroscopic, for example, and can be damaged by emulsified oil or solvent mist. With polymer optics, such contaminants may not affect surface finish, but would negatively affect the durability and performance of optical coatings applied to finished parts. Thus, there is a need for removal mechanisms that can effectively cool and clean the cutting diamond as well as keep the cutting surface clear of swarf or other residue in order to provide uniform form and finish, particularly for optical polymer materials.